My advice to prospective PhD students is to follow your passion and pick a topic that interests you — don't do a PhD topic that you hate, but you think will be lucrative. Because the big picture is that it is the fundamentals learned and problem solving skills gained from your PhD that will open the real career doors. Topics come in and out of fashion — it is the investment in yourself and the person you become through your PhD experience that really matters in the end. Of course, if you happen to love a topic that turns out lucrative then great — but this is hard to predict.

My starting point is as an academic who always thought nuclear was the answer, but who then looked at the figures and came to an inescapable conclusion that solar-hydrogen is the long-term future. I did not come at this as a green evangelist. I am a reluctant convert.

One can justify solar-hydrogen simply on grounds of economic resource viability without any green agenda.

The fact that there simply is 5,000 times more sun power than our consumption needs makes me very optimistic. It's a fantastic resource. We have the ingenuity to send man to the moon, so we definitively have the ingenuity to tap the sun's resources.

The biggest challenge [for solar power] is escaping from the economic effects of vendor lock-in where large investments in nuclear and traditional energy sources keep us 'locked-in' to feeding monsters that will bring us down an economic black hole. It's rather like the play The Little Shop of Horrors where a man-eating plant is initially fed small amounts, but then its voracious appetite sends it into a downward spiral swallowing up anyone that gets in its way.

Efficiency is not the issue when you go solar. There is so much solar that all you have to do is invest in the non-recurring cost of more dishes to drive a solar-hydrogen economy at whatever efficiency it happens to sit at.